Quantum master equations for entangled qubit environments

TL;DR

This paper derives quantum master equations for systems interacting with entangled qubit environments, revealing conditions for entanglement generation and the impact of environmental coherences on system dynamics.

Contribution

It introduces a framework for modeling Markovian dynamics with entangled qubit baths and analyzes their effects on remote quantum systems.

Findings

Antidiagonal coherences are necessary for entangling remote systems.

Maximally entangled baths are exceptional points without unique steady states.

Environmental coherences do not affect system evolution in weak coupling regimes.

Abstract

We study the Markovian dynamics of a collection of n quantum systems coupled to an irreversible environmental channel consisting of a stream of n entangled qubits. Within the framework of repeated quantum interactions, we derive the master equation that describes the dynamics of the composite quantum system. We investigate the evolution of the joint system for two-qubit environments and find that (1) the presence of antidiagonal coherences (in the local basis) in the environment is a necessary condition for entangling two remote systems, and (2) that maximally entangled two-qubit baths are an exceptional point without a unique steady state. For the general case of n-qubit environments we show that coherences in maximally entangled baths (when expressed in the local energy basis), do not affect the system evolution in the weak coupling regime